DSC study of the symdialchylsuphoxides on the thermal denaturation of lysozyme solutions

Sym-dialchylsulfoxides (DASO), with both the hydrophilic and hydrophobic character, are able to destabilize the native structure of proteins by weakening hydrophobic interactions between non-polar residues as well by perturbing the structure of water surrounding the protein molecule. They showed effective cryoprotective effect on living system, more enhanced in the presence of diethylsulfoxide (DESO) than of dimethylsulfoxide (DMSO) or di-n-propylsulfoxide (DnPSO) (1). The knowledge of the influence of DASO on the thermal denaturation and to the structural stability of protein is essential to understand their role in the cryoprotective effect and we approached this problem by studying the thermal denaturation of lysozyme by means of Differential Scanning Calorimetry (DSC).